Influence of the menstrual cycle on crawl performance in young female swimmers

To determine the influence of the phases of the menstrual cycle on swimming performance, analyzing the variation of performance in the variables time, frequency and duration of the swimming cycle in crawl style, efficiency index and average speed developed. Eleven regional high-performance swimmers were recruited. The intervention was carried out in 3 phases of the menstrual cycle (menstrual phase (FM); follicular phase (FF) and luteal phase (FL) which consisted of a 2 x 50 m test with 5 minutes of recovery in crawl style. The 50-metre time (T50), cycle frequency (CF), cycle length (CL), mean velocity (MV) and efficiency index (EI) were analyzed. For comparisons between menstrual cycle times, a T-Student for related samples was applied. Effect size was calculated using Cohen's d. There are significant differences in performance as a function of menstrual cycle phase. MP vs FP: T50 [30.41 (1.47) sec] vs [29.86 (1.56) sec] 1.91% (D=0.36); CL [46.01 (3.92) cycles/min] vs [47.15 (4.03) cycles/min] 2.5% (D=0.28); MP vs LP: CL [1.99 (0.13) cycles/min] vs [2.01 (0.14) cycles/min] 1.01% (D=0.13) FP vs LP: CL [1.97 (0.15) m/cycle] vs [2.01 (0.14) m/cycle] 2.03% (D=0.27%) IE p